1. Field of the Invention
This invention relates to a nail driver for driving a nail on a material with a driving power.
2. Description of the Prior Art
Nail drivers for nailing with driving power are known. Such a nail driver has a piston and a driving unit for hitting a nail to drive a nail into a material. FIG. 9 is a sectional view of such a prior art nail driver which includes an outputting portion having a cylinder and a piston for generating a drive force from a pneumatic force, a handle portion perpendicularly extending from the outputting portion, a magazine for containing nails 50 which are intermittently supported along wires 10, and a nose portion 4 including a tubular nozzle 105 for guiding the nail 50 received from the magazine 3 and hit by the piston 8.
The nail 50 is supplied to the nozzle 105 through an opening 6 at a rear portion of the nozzle 105 by a supplying mechanism 7 including an air cylinder and an air piston. The nail 50 supplied to the nozzle 105 is struck by piston 8. The bore of the nozzle 105 is generally made as small as the head of the nail 50 can just pass therethrough.
The nail 50 travels along the wall of the nozzle 105 so that almost all nails 50 are driven into a board 9 perpendicularly as shown in FIGS. 15 and 16. However, the struck nail 50 may be inclined from the axis of the nozzle 105 as shown in FIG. 11. Such a nail is driven into the board 9 with inclination as shown in FIGS. 12 and 13.
Referring now to FIGS. 9 to 14, we illustrate this operation more specifically. The nails 50 are linked with wires 10 and successively supplied to the nozzle 105 through the magazine 3. The piston 8 is rapidly driven downwardly (in the drawings) in response to a trigger. Next, the piston 8 hits the nail 50 so that the wires 10 are disconnected as shown in FIG. 10. The nail 50 travels downwardly together with the pieces of wires 10 through the nozzle 105. During this operation, the nail 50 may be inclined from the axis of the nozzle 105 as shown in FIG. 11 because a side of the head 51 of the nail 50 strongly may contact with the inner wall of the nozzle 105 for example. If the nail 50 is being driven by the piston 8 in this condition, the nail 50 strikes the board 9 with inclination as shown in FIGS. 12 and 13, so that the nail 50 sticks in the board 9 with bend thereof as shown in FIG. 14, wherein the head 51 is also bent. This is because the driving point is shifted from the tip 52 of the nail 50. Moreover, this causes direct hitting the board 9 by the piston 8.
This condition provides a poor appearance of the board 9 and a poor holding power. Moreover, if nails 50 for fixing a sheet 11 of which head size is relatively large and the length is relatively short are used, this erroneous operation will break the sheet 11. That is, there are problems that the nail is struck with inclination so that the driven nail is bent, and this provides a poor appearance and low holding power.
The aim of the present invention is to provide a superior nail driver.
According to the present invention, a first aspect of the present invention provides a nail driver comprising: a driving portion having a trigger and a piston coupled to a driving unit for driving a nail in a driving direction in response to said trigger; a handle connected to said driving portion; a tubular guide portion having an output nozzle for guiding said nail driven by said driving portion and outputting said nail through said output nozzle, an axis of said tubular guide portion being arranged in said driving direction; and a magazine connected to said tubular guide portion for supplying said nail to said tubular guide portion, wherein an inner surface of said tubular guide portion has a taper extending in said driving direction near said output nozzle to direct a tip of said nail toward an axis of said tubular guide portion when said tip of said nail contacts with said taper.
According to the present invention, a second aspect of the present invention provides a nail driver based on the first aspect, wherein a cross-sectional area of said taper progressively decreases in said driving direction.
According to the present invention, a third aspect of the present invention provides a nail driver based on the first aspect, wherein said inner surface further includes another taper extending in an opposite driving direction, provided upstream from said taper.
According to the present invention, a fourth aspect of the present invention provides a nail driver based on the third aspect, wherein another cross-sectional area of said another taper progressively increases in said driving direction.
According to the present invention, a fifth aspect of the present invention provides a nail driver based on the fourth aspect, wherein said taper and said another taper are arranged coaxially with said axis of said tubular guide portion.
According to the present invention, a sixth aspect of the present invention provides a nail driver based on the third aspect, wherein a first slope of said taper on a plane including said axis of said tubular guide portion makes a first angle with said axis and a second slope of said another taper on said plane makes a second angle with said axis, and said second angle is smaller than said first angle.
According to the present invention, a seventh aspect of the present invention provides a nail driver based on the sixth aspect, wherein said first angle is about 15xc2x0 and said second angle is about 2xc2x0.
According to the present invention, an eighth aspect of the present invention provides a nail driver based on the third aspect, wherein a diameter of an upstream end of said another taper is equal to a diameter of a downstream end of said taper.
According to the present invention, a ninth aspect of the present invention provides a nail driver based on the third aspect, wherein said taper and said another taper is successively connected.